The Developmental Therapeutics Program of the Division of Cancer Treatment (DCT), National Cancer Institute, is conducting a program for the discovery and pre-clinical development of new anticancer drugs. This project is designed to provide for: the in vivo screening of new synthetic and natural products for activity against transplantable rodent tumors and detailed evaluation of materials showing activity in DCT antitumor screens with respect to factors influencing antitumor selectivity; study of the influence of synthetic and natural products on immunological parameters which may modify chemotherapeutic effectiveness; and pharmacological studies on selected antitumor drugs.